Benchtop instrument simulator for CERES EOS-AM1

John J. Chapman

doi:10.1117/12.325641

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3 October 1998 Benchtop instrument simulator for CERES EOS-AM1

John J. Chapman

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Proceedings Volume 3439, Earth Observing Systems III; (1998) https://doi.org/10.1117/12.325641
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1998, San Diego, CA, United States

Abstract

The first CERES instrument was launched on NASA/NASDA's Tropical Rainfall Measurement Mission (TRMM) platform Nov. 28, 1997. More CERES instruments will soon be launched on NASA's Earth Observing System (EOS) satellites. CERES measures top of the atmospheric radiative fluxes using microprocessor controlled scanning radiometers. The CERES EOS-AM1 Instrument Simulator will serve as a testbed for the testing of custom instrument commands intended to solve in- flight anomalies of the instruments which could arise during the CERES EOS-AM1 mission. The concept of using an identical but non-flight qualified microprocessor and electronics ensemble linked to a virtual instrument PC running modeling software results in a relatively inexpensive simulation system capable of high fidelity. The first CERES Instrument Simulator resembles the TRMM CERES instrument sufficiently well to allow benchtop testing and functional verification of microprocessor loads for TRMM instrument unloads, circuitry identical to the flight unit's twin microprocessors and telemetry interface to the supporting spacecraft electronics and two personal computers (PC) connected to the I/O ports that control azimuth and elevation gimbals. Flight simulation software consists of the unmodified TRW developed Flight Code and Ground Support Software specific to the platform under study which serves as the instrument monitor and also links NASA/TRW developed engineering models of the gimballed instrument. The CERES engineering development software models were modified to provide a virtual instrument running in real-time on a second PC linked to the flight microprocessors instrument control ports. The cost of the electronics and development of such a simulation system is dwarfed by the cost to develop the actual flight software, which has already been invested in building the actual instrument. Thus for the simulator, flight software re-use is very cost effective. The concept of using dedicated electronics and specific flight software matched to the instrument being studied allows for high fidelity simulations of each instrument system. The differences in flight code that represent the final flight configurations from platform to platform are accurately modeled. The overall task of tailoring the simulation system hardware to a given instrument platform reduces to the art of interfacing and programming a pair of embedded microprocessors linked to a pari of commercially available PCs.

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John J. Chapman "Benchtop instrument simulator for CERES EOS-AM1", Proc. SPIE 3439, Earth Observing Systems III, (3 October 1998); https://doi.org/10.1117/12.325641

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